Is it possible for you to borrow a buddy's amp? You can hook it up to your existing wiring to rule out a bad amp. The downside however, is if there's an installation error, you could damage your buddy's amp.
Also, you could try hooking up one woofer at a time. If the amp plays one woofer fine and then you hook up the second one and it shuts off, you have a bad woofer.